Sequential and coexisting bilateral suboccipital cavernous sinus arteriovenous fistulas successfully treated with unilateral transvenous coil embolization: illustrative case.

Background: The suboccipital cavernous sinus (SCS) is a venous compartment surrounding the horizontal segment of the vertebral artery (VAh), from the transverse foramen of the atlas (C1) to the dura mater at the foramen magnum. The SCS is structurally and functionally similar to the cavernous sinus (CS). The CS is frequently involved in dural arteriovenous fistulas (DAVFs), and bilateral CS-DAVFs are not rare. However, SCS-arteriovenous fistulas (SCS-AVFs) are extremely rare, with no documented cases of bilateral occurrence.

Observations: A 58-year-old renovation worker presented with a right SCS-AVF and pulsatile tinnitus, which worsened at night. After diagnostic cerebral angiography, his tinnitus slightly improved, but worsened again 6 months later, becoming bilateral and significantly affecting his sleep and daily life. Repeat cerebral angiography demonstrated decreased feeding arteries and draining veins of the right SCS-AVF, with a new left SCS-AVF. Treatment of the dominant left SCS-AVF with ipsilateral transvenous embolization with coils (TVE-c) led to gradual improvement in residual SCS-AVFs, and the tinnitus completely disappeared within 1 year.

Lessons: Similar to bilateral CS-DAVFs, which can be obliterated with unilateral TVE-c, the bilateral SCS-AVFs in this patient were successfully managed with unilateral TVE-c. Treatment strategies for bilateral SCS-AVFs may therefore resemble those for bilateral CS-DAVFs. https://thejns.org/doi/10.3171/CASE25137.